The vanishing farmland myth: Tracking farmland loss to urbanization through the use of geospatial data

Expansion of urban areas into adjacent agricultural land has been viewed as a threat to local community, food stability and the American farming heritage. Protecting farmland from the proposed threat of urban expansion has been a part of local, state and federal government policy since the mid-20 th century. This paper will analyze one county's approach to farmland preservation through comparison of planning zone farmland loss rates.;Previous models of urban expansion and farmland loss have relied on data from the Census of Agriculture, the National Agriculture Lands Study (NALS), and the USDA National Agriculture Statistics Service (NASS) surveys to generate urban planning and policy initiatives. Data for these projects have relied on producer surveys and ignore changes in crop rotation, land in fallow, conversion to urban land use and the total production of major crops (corn, wheat and soybeans) as a measure of food security and the resulting threat of urbanization. An inconsistent definition of farmland, cropland and land in farms has lead to questions about the presence or absence of "farmland loss". In order to accurately assess the threat of urbanization to farmland quantity and quality, it is necessary to generate a conversion rate.;The method for determining a farmland loss to urbanization rate was designed to utilize real time geographic data about the presence of crop acreage where, a "farm" refers to all crop acreage in all counties that a producer planted or intended to be planted for harvest for normal commercial sale or farm livestock feeding. Land cover data for 2007-2009 from the National Agricultural Statistics Service (NASS) was analyzed to compute a farmland to urban conversion rate. Analysis to determine growth rates within the three urban planning zones of Kane County was performed, and an analysis of the amount and pattern of agricultural land conversion in Kane County from 2007 to 2009 was performed in conjunction with agricultural land productivity data. Two models of future growth are developed, the first incorporating the concept of growth and the second incorporating discontinuous development pattern. The analysis of land use change showed an average loss of 149.5 acres of farmland to residential land use per year in Kane County. This development occurred at rates that suggest the achievement of planning policy goals amidst increasing farmland productivity. Furthermore, the land use change analysis suggests that using remotely sensed data may result in an over-estimation of farmland loss which may lead to erroneous rates of yearly farmland loss.